CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Shares Held Under Employee Participation Plan	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Earnings
Beginning balance at Dec. 31, 2016	$ 1,084,241	$ 573	$ (469)	$ 725,670	$ (214,326)	$ 572,793
Beginning balance (in shares) at Dec. 31, 2016		57,298
Increase (Decrease) in Stockholders' Equity
Net income	100,739					100,739
Other comprehensive income (loss)	41,919				41,919
Stock-based compensation	13,146			13,146
Issuance of common stock for restricted share vesting, net of employee tax withholding	(3,149)	$ 1		(3,150)
Issuance of common stock for restricted share vesting, net of employee tax withholding (in shares)		133
Exercise of stock options	46			46
Exercise of stock options (in shares)		2
Repurchases of common stock	$ (48,971)	$ (9)		(48,962)
Repurchases of common stock (in shares)	(900)	(907)
Shares held under employee participation plan	$ 0		469	(469)
Shares held under employee participation plan (in shares)		(25)
Ending balance at Dec. 31, 2017	1,188,202	$ 565	0	686,962	(172,407)	673,082
Ending balance (in shares) at Dec. 31, 2017		56,501
Increase (Decrease) in Stockholders' Equity
Net income	65,636					65,636
Other comprehensive income (loss)	(50,964)				(50,964)
Stock-based compensation	16,792			16,792
Issuance of common stock for restricted share vesting, net of employee tax withholding	(3,266)	$ 1		(3,267)
Issuance of common stock for restricted share vesting, net of employee tax withholding (in shares)		160
Repurchases of common stock	$ (45,080)	$ (8)		(45,072)
Repurchases of common stock (in shares)	(800)	(814)
Ending balance at Dec. 31, 2018	$ 1,169,756	$ 558	0	655,415	(223,371)	737,154
Ending balance (in shares) at Dec. 31, 2018		55,847
Increase (Decrease) in Stockholders' Equity
Net income	97,740					97,740
Other comprehensive income (loss)	13,320				13,320
Stock-based compensation	17,816			17,816
Issuance of common stock for restricted share vesting, net of employee tax withholding	(7,429)	$ 3		(7,432)
Issuance of common stock for restricted share vesting, net of employee tax withholding (in shares)		249
Repurchases of common stock	$ (21,390)	$ (3)		(21,387)
Repurchases of common stock (in shares)	(300)	(298)
Ending balance at Dec. 31, 2019	$ 1,269,813	$ 558	$ 0	$ 644,412	$ (210,051)	$ 834,894
Ending balance (in shares) at Dec. 31, 2019		55,798